Optical data transceiver modules convert optical signals received via an optical fiber into electrical signals, and convert electrical signals into optical signals for transmission via an optical fiber. In the transmitter portion of a transceiver module, an opto-electronic light source such as a laser performs the electrical-to-optical signal conversion. In the receiver portion of the transceiver module, an opto-electronic light detector such as a photodiode performs the optical-to-electrical signal conversion. A transceiver module commonly also includes optical elements or optics, such as lenses, as well as electrical circuitry such as drivers and receivers. A transceiver module also includes one or more connector receptacles to which an optical fiber cable can be connected. The light source, light detector, optical elements and electrical circuitry can be mounted within a module housing.
Various transceiver module configurations are known. One family of transceiver module configuration is known as Small Form Factor Pluggable (SFP) and includes variations such as SFP+, Quad SFP (QSFP), etc. Such SFP-family transceiver modules include an elongated housing having a substantially rectangular cross-sectional shape, i.e., a bar shape. A forward end of the housing, sometimes referred to as the nose, has one or more receptacles into which optical fiber connectors can be plugged. A rearward end of the housing has an array of electrical contacts that can be plugged into a mating connector when the rearward end is inserted or plugged into a slot of a network switch or other device.
A common type of optical fiber connector is known as LC. As illustrated in FIG. 1, an LC plug 10 has a flexible latch arm 12 and a plug body 14. An end of latch arm 12 joins a sidewall of plug body 14 to form a hinge-like, bendable or resiliently flexible joint. Substantially at this joint, latch arm 12 can resiliently flex about an axis 16. Latch arm 12 is made of a material such as resilient plastic to facilitate such flexure. As further illustrated in FIG. 2, in response to a force having a component generally in the direction indicated by the arrow 18, latch arm 12 can be flexed from a relaxed or unflexed state shown in solid line to a fully flexed state shown in broken line. The force thus loads latch arm 12 with a return spring force or resilient bias force. When the force is removed, the spring force or resilient bias force returns latch arm 12 to the relaxed state. In the relaxed state, the angle 20 between a centerline 22 of latch arm 12 and a central axis 24 of LC plug 10 is commonly between about 15 and 25 degrees, and latch arm 12 can be flexed to essentially any angle within that range.
As illustrated in FIG. 3, LC plug 10 terminates the end of a fiber-optic cable 26. LC plug 10 can be plugged into a receptacle in a nose 28 of an optical transceiver module 30. For illustrative purposes, optical transceiver module 30 has a QSFP configuration. A region 32 of FIG. 3 is shown enlarged in FIG. 4 to more clearly illustrate the manner in which LC plug 10 engages nose 28 in a pluggable and latchable manner. As LC plug 10 is inserted into the receptacle, interior surfaces of the receptacle (not shown in FIGS. 3-4) receive and guide plug body 14 (FIGS. 1-2), and a slot in a wall 31 of the receptacle receives and guides portions of latch arm 12. Also, as LC plug 10 is inserted into the receptacle, a ramp portion 29 of latch arm 12 slides against an interior surface of wall 31, thereby initially applying the above-referenced force indicated by arrow 18 in FIG. 1. In response to this force, latch arm 12 flexes in the manner described above.
Latch arm 12 has two projections or blocks 34 and 36 located approximately mid-way along the length of latch arm 12 at the end of ramp portion 29. The effect of blocks 34 and 36 bearing against the interior surface of wall 31 while LC plug 10 is being inserted restrains latch arm 12 in a partly flexed state.
As LC plug 10 is still further inserted into the receptacle in nose 28, blocks 34 and 36 slide over an edge of wall 31 defined by two faces or catches 38 and 40. An end of the above-referenced slot in wall 31 is between catches 38 and 40. As blocks 34 and 36 slide over the end of the slot and no longer bear against the interior surface of wall 31, latch arm 12 is released from restraint. The spring force flexes latch arm 12 into the fully relaxed state. As latch arm 12 flexes into the fully relaxed state, blocks 34 and 36 snap into a latched position against catches 38 and 40. This latching engagement, in which blocks 34 and 36 bear against catches 38 and 40, resists LC plug 10 from being withdrawn from the receptacle. To disengage or de-latch LC plug 10 from the receptacle, a person can apply the force described above with regard to FIG. 2 and withdraw (i.e., un-plug) LC plug 10 from the receptacle. Latch arm 12 has an actuator end 21 that is conveniently shaped for a person to apply the force with a finger.
Although for purposes of clarity only a single LC plug 10 is shown plugged into a single receptacle in nose 28, nose 28 includes four such receptacles (as the illustrated optical transceiver module 30 is of the QSFP type). The term “receptacle” refers to an interior region of nose 28 that interfaces with portions of LC plug 10. The receptacle is defined principally by two cavities or three-dimensional regions that can be referred to as a keyway and a latchway. In the illustrated nose 28, the keyway of each receptacle has a substantially square cross-sectional shape corresponding to the substantially square cross-sectional shape of plug body 14, so that plug body 14 is guided into the receptacle when LC plug 10 is inserted. The keyway thus extends in the direction in which LC plug 10 is inserted into the receptacle. The latchway extends laterally or transversely from the keyway and includes the above-referenced slot in wall 31. The latchway accommodates the flexure of latch arm 12. That is, latch arm 12 can move within the latchway as it flexes between the fully flexed state and fully relaxed state. In FIG. 4, latch arm 12 is shown in a fully relaxed state, extending through the latchway slot. Note that actuator end 21 of latch arm 12 extends outside the outline of the module housing.